undefined method `before' for nil:NilClass

[yegor256]

Traceback (most recent call last):
	10: from /Users/yegor/.rvm/gems/ruby-2.7.0/bin/ruby_executable_hooks:24:in `<main>'
	 9: from /Users/yegor/.rvm/gems/ruby-2.7.0/bin/ruby_executable_hooks:24:in `eval'
	 8: from /Users/yegor/.rvm/gems/ruby-2.7.0/bin/xcop:23:in `<main>'
	 7: from /Users/yegor/.rvm/gems/ruby-2.7.0/bin/xcop:23:in `load'
	 6: from /Users/yegor/.rvm/gems/ruby-2.7.0/gems/xcop-0.7.1/bin/xcop:94:in `<top (required)>'
	 5: from /Users/yegor/.rvm/gems/ruby-2.7.0/gems/xcop-0.7.1/lib/xcop/cli.rb:59:in `fix'
	 4: from /Users/yegor/.rvm/rubies/ruby-2.7.0/lib/ruby/2.7.0/set.rb:328:in `each'
	 3: from /Users/yegor/.rvm/rubies/ruby-2.7.0/lib/ruby/2.7.0/set.rb:328:in `each_key'
	 2: from /Users/yegor/.rvm/gems/ruby-2.7.0/gems/xcop-0.7.1/lib/xcop/cli.rb:60:in `block in fix'
	 1: from /Users/yegor/.rvm/gems/ruby-2.7.0/gems/xcop-0.7.1/lib/xcop/document.rb:59:in `fix'
/lib/nokogiri/xml/node_set.rb:63:in `before': undefined method `before' for nil:NilClass (NoMethodError)